99.95% uptime: 4.4 h of downtime a year, and what it costs
An uptime target is a downtime budget written in a friendlier font. Here is what 99.95% allows, in every period people care about, and what those hours cost against revenue and against the people who fight the fire.
99.95% uptime allows 4.4 h of outage a year — about 22 min a month, 5 min a week.
How much downtime 99.95% allows
| Period | Downtime allowed |
|---|---|
| Per year | 4.4 h |
| Per quarter | 1.1 h |
| Per month | 22 min |
| Per week | 5 min |
| Per day | 1 min |
What those hours cost
| Annual revenue | Revenue / hour | Lost per year |
|---|---|---|
| $1,000,000 | $114 | $500 |
| $10,000,000 | $1,142 | $5,000 |
| $50,000,000 | $5,708 | $25,000 |
| $250,000,000 | $28,540 | $125,000 |
| $1,000,000,000 | $114,200 | $500,000 |
Assumes a 24/7 service with outages spread evenly, no SLA credits and no churn. Real outages cluster in business hours and cost more, so treat this as a floor.
The people on every incident
An outage is not only lost revenue: it is the most expensive hours in the company, usually outside working hours. At employer cost for a senior engineer (United States, $85.12 an hour), 3 people on every incident costs $1,118 a year at this tier — before a single sale is missed.
What the next nine buys
Run it with your own revenue
Put in your own revenue, the share of it that stops during an outage, and how many people get paged. The tier is already set to 99.95%.